Quanbin Zhang

Potential antioxidant and anticoagulant capacity of low molecular weight fucoidan fractions extracted from Laminaria japonica.

A low molecular weight fucoidan (DFPS), obtained from the brown seaweed Laminaria japonica, was separated into three fractions by anion-exchange column chromatography. All three fractions (DF1, DF2, DF3) predominantly contained variety fucose, galactose and sulfate group. The antioxidant and anticoagulant activities of these fractions were investigated. The results showed that all fractions possessed considerable antioxidant activities, DF1 was most active. All samples inhibited coagulant in APTT, TT and PT assays obviously. Available data presented the content of sulfate group, the molar ratio of sulfate/fucose and sulfate/total sugar, and the molecular weight played an important role on antioxidant and anticoagulant activity.

Antioxidant activity of different molecular weight sulfated polysaccharides from Ulva pertusa Kjellm (Chlorophyta)

Polysaccharides extracted from Ulva pertusa Kjellm (Chlorophyta) are a group of sulfated heteropolysaccharides, the ulvans. In this study, different molecular weight ulvans were prepared by H2O2 degradation and their antioxidant activities investigated including superoxide and hydroxyl radical scavenging activity, reducing power and metal chelating ability. The molecular weights of natural and degraded ulvans were 151.7, 64.5, 58.0, and 28.2 kDa, respectively, as determined by high performance gel permeation chromatography. Among the four samples, U3 (the lowest molecular weight sample) showed significant inhibitory effects on superoxide and hydroxyl radicals with IC50 values of 22.1 μ g mL−1 and 2.8 mg mL−1; its reducing power and metal chelating ability were also the strongest among the four samples. All the other samples also demonstrated strong activity against superoxide radicals. The results indicated that molecular weight had a significant effect on the antioxidant activity of ulvan with low molecular weight ulvan having stronger antioxidant activity.

In vivo antioxidant activity of polysaccharide fraction from Porphyra haitanesis (Rhodephyta) in aging mice.

Sulfated polysaccharide fraction F2 from Porphyra haitanesis (Rhodephyta) showed inhibitory effect on the in vitro lipid peroxidation. In the present study, the age-related changes in the antioxidant enzyme activity, lipid peroxidation, and total antioxidant capacity (TAOC) in different organs in mice were investigated and the in vivo antioxidant effect of F2 in aging mice was checked. Increased endogenous lipid peroxidation and decreased TAOC were observed in aging mice. Intraperitoneal administration of F2 significantly decreased the lipid peroxidation in a dose-dependent manner. F2 treatment increased TAOC and the activity of superoxide dismutase (SOD) and glutathione peroxidase (GSH-Px) in all the organs tested in aging mice. It is concluded that the sulfated polysaccharide fraction F2 can be used in compensating the decline in TAOC and the activities of antioxidant enzymes and thereby reduces the risks of lipid peroxidation.

Antioxidant activities of sulfated polysaccharide fractions from Porphyra haitanesis

Three sulfated polysaccharide fractions (F1, F2, and F3) were isolated from Porphyra haitanesis, an important economic alga in China, through anion-exchange column chromatography and their in vitro antioxidant activities were investigated in this study. Galactose was the main sugar unit of the three fractions. The analytical results indicated that polysaccharide fractions from P. haitanesis had similar chemical components to porphyran from other species, but differed in their high sulfate content. The sulfate content of F1, F2 and F3 was 17.4%, 20.5% and 33.5% respectively. All three polysaccharide fractions showed antioxidant activities. They had strong scavenging effect on superoxide radical, and much weaker effect on hydroxyl free radical. Lipid peroxide in rat liver microsome was significantly inhibited, and H2O2 induced hemolysis of rat erythrocyte was partly inhibited by F1, F2 and F3. Among them, F3 showed strongest scavenging effect on superoxide radical; F2 had strongest effect on hydroxyl radical and lipid peroxide.

Structural studies on a novel fucogalactan sulfate extracted from the brown seaweed Laminaria japonica.

A low molecular weight fucogalactan, obtained from the brown seaweed Laminaria japonica, was separated into three fractions (LF1, LF2 and LF3) by DEAE-Sepharose FF column chromatography. All three fractions contained predominantly fucose, sulfate group and galactose. The results showed that the main fraction LF2 consisted of l-fucose, d-galactose and sulfate at a molar ratio 6:1:9. Structural study on the LF2 was carried out by NMR spectroscopy. The backbone of LF2 was primarily (1-->3)-linked alpha-l-fucopyranose residues (75%) and a few (1-->4)-alpha-l-fucopyranose linkages (25%). The branch points were at C-4 of 3-linked alpha-l-fucopyranose residues by beta-d-galactopyranose unites (35%, molar ratio) or at C-2 of 3-linked alpha-l-fucopyranose residues by non-reducing terminal fucose unites (65%, molar ratio). Sulfate groups occupied at position C-4 or C-2, sometimes C-2, 4 to fucose residues, and C-3 and/or C-4 to galactose residues. The structure of LF2 was supposed as following: .

Synthesized phosphorylated and aminated derivatives of fucoidan and their potential antioxidant activity in vitro.

Three sulfated polysaccharide derivatives (phosphorylated and aminated fucoidan) were synthesized, and their potential antioxidant activities were investigated employing various established in vitro systems. Two methods were used in phosphorylation fucoidan: polyphosphoric acid and POCl(3) method. Aminated fucoidan was prepared using the epichlorohydrin and ammonia water. All fucoidan derivatives possessed considerable antioxidant activity, and exhibited stronger antioxidant ability than fucoidan in certain tests. The phosphorylated fucoidan showed stronger hydroxyl radical and 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical scavenging activity and reducing power. The mechanism on influence the antioxidant activity of samples of phosphate and amino group was indicated.

Preparation of the different derivatives of the low-molecular-weight porphyran from Porphyra haitanensis and their antioxidant activities in vitro

Porphyran extracted from Porphyra haitanensis is a sulfated polysaccharide, which possesses excellent antioxidant activities. In this study, we prepared one low-molecular-weight porphyran and its sulfated, acetylated, phosphorylated and benzoylated derivatives. Their antioxidant activities were investigated including scavenging effect of superoxide, hydroxyl and 1,1-diphenyl-2-picrylhydrazyl radicals. The results of chemical analysis and FT-IR spectrums showed the modification was successful. And in addition, we found that certain derivative exhibited stronger antioxidant activity than low-molecular-weight porphyran. The benzoylated derivative showed the most excellent antioxidant activity in three assays, so this derivative needs to be attended to.

Hypoglycemic property of acidic polysaccharide extracted from Saccharina japonica and its potential mechanism

In the present study, a sulfated polysaccharide fucoidan extracted from Saccharina japonica was administered to normal and alloxan-diabetic rats/mice, and its effects on glycemia, insulin and serum lipid levels were evaluated. Fucoidan administered at 200 or 1200 mg/kg body weight/day could significantly reduce the blood glucose level by 22% and 34%, respectively, in alloxan-induced diabetic rats. Serum insulin levels in diabetic mice were increased by the administration of fucoidan (P<0.05). The results of an oral glucose tolerance test (OGTT) revealed that fucoidan treatment had some effect on glucose disposal after 15 days of treatment. Furthermore, fucoidan altered plasma lipid levels by lowering cholesterol, triglyceride and plasma low-density lipoprotein concentrations, while elevating plasma high-density lipoprotein cholesterol at 100 or 300 mg/kg body weight/day. The results suggested that fucoidan exhibited a considerable hypoglycemic effect, possibly by stimulating pancreatic release of insulin and/or by reducing insulin metabolism. Our results indicated that fucoidan could be developed as a potential oral hypoglycemic agents or functional food for the management of diabetes.

A comparative study of the anticoagulant activities of eleven fucoidans.

Seven fucoidans that differed only with respect to the average molecular weight and four fucoidans that differed with respect to both the molar ratio of fucose to galactose and the average molecular weight were obtained. The anticoagulant activities of these fucoidans were determined in order to understand the effects of the average molecular weight and the content of galactose. Fucoidans Y5-Y11, with the average molecular weight in the range of 50.1-8.4 kDa, showed decreasing activity at three concentrations and dose-dependent activity in the APTT and TT assays. Y1-Y4, which differed with respect to the average molecular weight and the molar ratio of fucose to galactose, exhibited complicated results in the APTT and TT assays. It was shown that not only the average molecular weight but also the molar ratio of fucose to galactose affected the anticoagulant activity of fucoidans.

Effect and mechanism of fucoidan derivatives from Laminaria japonica in experimental adenine-induced chronic kidney disease

ETHNOPHARMACOLOGICAL RELEVANCE Laminaria japonica is a popular seafood and medicinal plant in China, Chinese people use them as a traditional medicine for curing edema disease, a symptom of kidney diseases. MATERIALS AND METHODS The renal protective activity and mechanism of fucoidan derivatives was studied against adenine induced CKD in rats. The fucoidan derivatives were administered at dose of 50 and 150 mg/kg body weight. The serum urea nitrogen (SUN), serum creatinine (SCR) and some enzymic activity were detected. RESULTS The SUN and SCR level decreased significantly with fucoidan derivatives administration. Histopathological changes of renal tubules and interstitium were markedly alleviated by fucoidan derivatives and the mesangial areas were also greatly reduced. Alterations were observed in the activities/levels of serum enzymic (CAT, GSH-PX) and non-enzymic (GSH) antioxidants, along with high level of malondialdehyde (MDA) in the CKD rats. However, normalized lipid peroxidation and antioxidant defenses occurred with fucoidan derivatives administration. CONCLUSION This study exhibited a new mechanism of fucoidan derivatives on CKD rats, that was the samples could alleviate renal tubules, interstitium and mesangial areas mediated by replacing the electronegative content of the glomerular cells and inhibition of mesangial cell proliferation. The study also proved the mechanism of fucoidan derivatives on the CKD rats had relationship with their antioxidant activities, the samples which could enhance the activity of antioxidant enzymes and reduce the LPO level could alleviate the symptom of CKD.